The invention relates to a reflective layer for the reflection of electromagnetic radiation and to a process for attenuating electromagnetic radiation.
The screening of residential and working premises as well as equipment against undesirable electromagnetic radiation gains increasing importance. Initially, in particular for the screening of premises interiors, special products were developed, nettings or non-woven webs of metal, in particular copper or of plastics into which metal fibres have been incorporated or vapour-coated with metal, in particular aluminium. Examples of this are Sisalex 514 of the firm Ampack, a composite of craft paper with inserted glass fibre netting and aluminium lamination, the protective panel “LaVita” of Knauf or the fabric “Cuprotect special” of the firm Kessel. Fabrics are marketed by the firm Biologa (“Picasso”) and the firm Genitex (“Genitnet 36”). The screening action is quite satisfactory, however these products provide only this single function. By their very nature, these products intended for interior application are neither waterproof nor weather-resistant.
For applications in exterior cladding and roofing, products have also been developed which are supposed to screen against electromagnetic radiation. In this context, in particular the products “Profilwelle und Sidings” of the firm Prefa (aluminium cladding elements), the “Sto-Abschirmvlies” of the firm AES (reinforcing fabric for thin layers of plaster), “XUND-E” a protective panel of natural plaster of Paris with a thin carbon coating of the firm Baufritz, “PIR-E-Protect”, an insulating panel coated on both sides with aluminium of the firm Bauder and “Delta-Reflex”, an aluminium-coated vapour barrier of the applicant should be mentioned. Although these products are already each suitable for two applications (e.g. insulation and screening or exterior cladding and screening), they are either not waterproof or—if waterproof—they are not water-vapour pervious.
The product “TOP-E-Protect” of the firm Bauder, a bituminised, laminated sheeting in which between a bitumen layer and a non-woven fabric a metal vapour coating had been applied, is watertight as well as pervious to water vapour.
If a vapour-coated layer has been furnished with a weatherproof coating—e.g. a bitumen coating—the vapour barrier can only be provided with potential compensation at unacceptable cost—if at all. The metal vapour coating, in practice, usually has only very limited inadequate weather resistance. The reason is that generally metal vapour coatings are employed of inexpensive and conventional types which are adversely affected by liquid water, in particular in the presence of atmospheric oxygen. The coatings are easily washed off and corroded, whereafter the conductivity of such reflective layer is no longer present.
Considering that even the highly adaptable TOP-E-Protect weatherproofing under layer of the firm Bauder, although suitable for multiple purposes, apart from its lacking weathering resistance, is unsuitable for connecting a potential compensation, its attenuation of electromagnetic radiation leaves much to be desired, because the protective sheeting itself returns part of the radiation back into the premises to be screened off. The undesirable effect of non-existing earthing becomes particularly noticeable if it is appreciated that such reflective layers transmit the fields issued by close-by power lines.